The long-term goal of this project is to develop a durable, reliable, second- generation, pulsatile Ventricular Assist Device (VAD), combining a proprietary magscrew actuator with a biolized blood pump. The actuator is similar to the magscrew Total Artificial Heart (TAH) actuator now under development The magscrew offers to the VAD the same benefits of reduced wear, no fatigue, and essentially lossless conversion of rotational motion to translational actuation, as is being demonstrated in the TAH. However, absence of the right-side pumping chamber changes envelope constraints, and permits actuator packaging in an even more optimal form. It also enables the major innovation of this application, the addition of a "magspring" to the actuator. With only one pumping chamber, the return stroke of the actuator can be used to store energy in the magspring, which reduces the loads and energy consumption during the VAD power stroke. This, in turn, enables the use of smaller actuator components, while maintaining or increasing life and reliability. The specific aims are to: I) design magsprings of appropriate size and force characteristics; 2) experimentally validate the magspring calculations; 3) fabricate and test an integrated magscrew and magspring actuator; and 4) lay out the package and define VAD performance with an optimal magscrew/magspring actuator. PROPOSED COMMERCIAL APPLICATIONS:Studies have predicted that there are 35,000 to 70,000 candidates annually for mechanical circulatory support, perhaps 70 to 80% requiring VADs and the remainder justifying the use of a TAH. A sufficiently safe, effective system could have a market as large as 200,000 cases per year, if its use in patients "only"' incapacitated by heart disease was justified. This is the commercial opportunity and social need to be addressed by the proposed research.